The goal of the proposed research is to contribute to the development of a process based theory of intelligence, within which the nature of the learning problems characterizing mentally retarded and learning disabled children can be described. In addition to this goal, we also propose to make use of the developing theoretical framework to guide attempts to devise instructional procedures to enhance the cognitive performance of our students. More precise specification of the problems confronting these children should enable us to come up with instruction more adequately tailored to the specific needs of the learner. To work toward these goals, we propose to conduct research in three areas. In one section, we explore the relation between cognitive status and molar aspects of behavior, notably speed of learning and breadth of transfer. This aspect of the work involves the use of dynamic assessment procedures and is based on the assumption that the use of such procedures can enrich the picture of children which emerges from more traditional assessments of ability. In the second section, we propose to investigate the extent to which various measures of processing efficiency and memory span are related to each other and to a number of alternative indices of general intellectual functioning. In the final section, we focus on the ability of students to make effective use of information known to be available to them.